Coated drying element

ABSTRACT

A FLEXIBLE, LIQUID PERMEABLE, DRYING ELEMENT, SUCH AS A THIN COATING, CONTAINING AN ORGANIC DESICCANT, TYPICALLY WITH A SYNTHETIC, POLYMERIC BINDING AGENT, IS USED FOR REMOVING A LIQUID, SUCH AS WATER, FROM A PERMEABLE SOLID, SUCH AS FROM ONE OR MORE LAYERS OFA PHOTOGRAPHIC ELEMENT CONTAINING WATER. FOR INSTANCE, A THIN COATING OF AN ORGANIC DISICCANT, SUCH AS A MIXTURE OF ETHYLENE OXIDE POLYMERS, REMOVES A LARGE PERCENTAGE OF THE WATER FROM A WET PHOTOGRAPHIC EMULSION LAYER. AN INORGANIC DESICCANT AND/OR OTHER ADDENDA CAN BE PRESENT IN THE THIN COATING.

United States Patent 1 3,591,411 COATED DRYING ELEMENT Paul W.Faulhaber, Rochester, N.Y., assignor to Eastman Kodak Company,Rochester, N.Y. No Drawing. Filed Dec. 26, 1967, Ser. No. 693,139 Int.Cl. D2111 l/28 U.S. Cl. 117--155UA 6 Claims ABSTRACT OF THE DISCLOSURE Aflexible, liquid permeable, drying element, such as a thin coating,containing an organic desiccant, typically with a synthetic, polymericbinding agent, is used for removing a liquid, such as Water, from apermeable solid, such as from one or more layers of a photographicelement containing water. For instance, a thin coating of an organicdesiccant, such as a mixture of ethylene oxide polymers, removes a largepercentage of the water from a wet photographic emulsion layer. Aninorganic desiccant and/ or other addenda can be present in the thincoatmg.

This invention relates to removing liquids from permeable solidmaterials containing such liquids. In one of its aspects, it relates toremoving diifusible liquid, such as water, from liquid permeable solidmaterials, such as a moist layer of a photographic element. In anotherof its aspects, it relates to drying a moist colloid coating bycontacting the moist coating with a supported or unsupported coatingcontaining an organic desiccant.

Two methods have generally been employed heretofore for removing liquidsfrom permeable solids containing such liquids. In one method, liquid isremoved by evaporation, for example, by a combination of heating thesolid and/ or reducing the pressure around the solid material. In thesecond method, the solid material is immersed in an extractant, such asremoving moisture from a moist photographic element by immersing themoist element in an extractant as set out in U.S. Pat. 2,150,757Bodine,issued Mar. 14, 1939.

These methods have not been satisfactory in many cases, especially forremoving moisture from photographic elements, since they require costlyequipment, such as apparatus for forcing heated air over the solidmaterial, require excessive time, often leave undesirable residue on thesolid dried, make the elements susceptible to accumulation of dust,and/or cause undesirable changes in the material dried.

In the case of photographic elements, it has been usual practice toprocess such elements after exposure in solutions or processing bathswhich produce a wet or moist product. It has been necessary in suchcases to wait, often for many minutes, for the film, paper, or the like,to dry before further processing or handling, such as contact printing,can be carried out. This time can be reduced by forced air drying atelevated temperatures but this method has not been entirely satisfactoryfor removing diffusible liquid from a photographic element in a matterof seconds without undesired effects to the element.

Drying of photographic elements processed without use of conventionalprocessing baths and where inspection of the processed element as soonas possible is desirable has been especially important. For example, inaerial reconnaissance, in radiology, and the like, it is necessary tohave the processed photographic element in dry condition as soon aspossible to determine results, to determine whether another exposureshould be made, and/or for other purposes. One method which has beenadvantageous in decreasing the time from exposure to finished product,without the use of conventional processing baths, employs a wet or moistabsorbent web containing processing compounds, typically a monobath,which is contacted with the exposed element for a desired length oftime. This method and means for carrying out the method are set out, forexample, in U.S. Pat. 3,l79,5l7-Tregillus et al., issued Apr. 20, 1965.One disadvantage of this method, however, is that the resultingprocessed photographic element is moist, as in other processes, afterthe film and web are separated and usually must be dried in some manner.Efforts to dry such a photographic element have included application ofa powdered inorganic drying agent, such as barium oxide, calciumchloride, activated alumina, and the like, dusted over the surface ofthe moist element or located on the surface opposite the film of aprotective porous web which is contacted with the moist film. This isdisclosed in British Pat. 1,012,391, is sued Dec. 8, 1965. In the casewhere the inorganic drying agent is dusted over the surface of the moistphotographic element, undesired adherence of the inorganic drying agentto the surface of the element can occur. On the other hand, when themoist photographic element is contacted with a semi-permeable membranewhich in turn is contacted with an inorganic drying agent, additionalmeans can be required for contacting the semi-permeable membrane withthe inorganic drying agent and removal of moisture can be less efiicientthan in the case of direct contact of the inorganic drying agent withthe moist element.

No process or means has been completely satisfactory heretofore foreliminating the costly air drying steps and apparatus employed forremoving moisture or other liquids from a moist layer of a photographicelement with direct contact of drying means on the layer.

Accordingly, an object of the invention is to provide novel means forrapidly removing liquid, such as Water, from a permeable solid, such asa layer of a photographic element, containing such liquid withoutundesired changes in the solid.

Another object is to provide a novel composition for removing a liquid,such as water, from a permeable solid, such as a photographic emulsioncoating, by contact of the composition with the permeable solid.

A further object is the provision of a means for rapidly removingditfusible liquid, such as water, from a photographic element withoutleaving undesirable residue on and/ or in the element.

The invention accordingly, comprises means, compos1- tions and processesfor rapidly removing liquid from a permeable solid material containingsuch liquid by contacting, preferably directly contacting, suchpermeable solid material with a flexible, liquid permeable, dryingelement comprising a solid coating containing an organic desiccant,without leaving undesirable residue and without adverse effects to thesolid material.

One embodiment of the invention, accordingly, comprises a flexible,liquid permeable, drying element comprising an organic desiccant in asynthetic polymeric binding agent different from said organic desiccant,e.g. having higher molecular weight or being different in composition.

This flexible, liquid permeable, drying element has the properties of(a) removing liquid from a permeable solid material containing suchliquid when the drying element and permeable solid material are incontact, and (b) after contact leaving little residue on the permeablesolid material.

Another embodiment comprises a flexible, liquid permeable, dryingelement which is a substrate having on at least one surface a thin,adherent, liquid permeable coating of an organic desiccant in asynthetic polymeric binding agent different from said organic desiccant.

A drying element of the invention typically has the property oftransferring no more than about 20 milligrams per square foot of bothsaid organic desiccant and said binding agent to a wet gelatin coatingupon contact with said coating for up to about 60 seconds. It alsotypically has the property of removing at least about 60%, for instance,more than about 85%, by weight of water from a wet gelatin layer coatedon a substrate upon contacting said layer for a period of no more thanabout 60 seconds with said drying element.

For instance, a drying element according to the invention can comprise asupport, typically a flexible support, having a solid, polymeric coatingcomprising an organic desiccant, which is a poly(alkylene oxide), with apoly meric binding agent different, e.g. having higher molecular weightor being different in composition, from said organic desiccant. Anespecially useful drying element, according to the invention, comprisesa flexible support having a solid, polymeric coating comprising apoly(ethylene oxide) having an average molecular weight of about 190 toabout 20,000 with a high molecular weight poly(ethylene oxide) binder,e.g. having an average molecular weight of about 100,000 to about5,000,000 or more. An especially useful drying element according to theinvention comprising a flexible support, such as paper or a polyethyleneterephthalate film, having a thin adherent coating of about 10% byweight poly(ethylene oxide) having an average molecular weight of about6000 to about 7500 with about 90% by weight of high molecular weightpoly (ethylene oxide) e.g. having an average molecular weight of about100,000 to about 5,000,000, can remove at least about 90% by weight ofthe water from a moist gelatin layer coated on a substrate uponcontacting said layer for a period of no more than about 60 seconds withsaid drying element.

The material comprising the organic desiccant and/r binder, if one isused, need not be present only on the surface of the support, if one isemployed. It can be present in and/or on the support. For example, partof the organic desiccant in the case of a poly(alkylene oxide) and/orbinder can be present in the support. The entire amount of thesematerials can be in the support or the entire amount can be on thesurface of the support if desired. Also, if desired, one or more of suchmaterials can be coated on one or more sides of a support, including theedges in the case of paper or film, for instance.

In some cases, a coating, according to the invention, has sufficientstrength that a support is not needed. Accordingly, the word coating asemployed herein is intended to include both supported and unsupportedcoatings. Unsupported coatings include, for example, self-supportingwebs, sheets, films, tape, and the like. Use of a support is oftenadvantageous, serving as a reservoir for liquid removed from thepermeable solid. For instance, a paper support coated with a polymericcoating according to the invention can hold a significant amount ofmoisture more than the coating alone.

Any suitable coating thickness can be employed. The coating thicknesscan vary over a wide range depending upon the material to be dried, thecomposition of the coating, the type of support if one is employed, theamount and type of liquid to be removed from the permeable solidmaterial, and the like. A suitable thickness comprises about 0.001millimeter to about 1.0 millimeter, typically about 0.01 to about 0.5millimeter, but a thickness outside this range can be used.

A wide range of binders can be employed in and/or on the drying elementsof the invention. In general, any binding agent can be employed with theorganic desiccant of the invention which provides a solid coating, underambient conditions, and which does not adversely affect the propertiesof the drying element, e.g. does not hinder liquid removal properties ofthe drying element and leaves little or no undesirable residue on thematerial from which liquid is removed.

The binder can be a desiccant. That is, if desired, both the organicdesiccant and the binder can efiect removal of liquid from a permeablesolid containing such liquid.

The organic desiccant can, but need not be, the same as the binder. Forinstance, in the case of poly(ethylene oxide), if the poly(ethyleneoxide) is sufiiciently solid, e.g. has sufiiciently high molecularweight, under ambient conditions, it need not be employed in combinationwith a binder, such as a poly(ethylene oxide) having an averagemolecular weight of about 100,000 to about 5,000,- 000. In this case,the organic desiccant can be used alone without a binder.

If a poly(ethylene oxide) having an average molecular weight of about190 to about 20,000 is employed as the organic desiccant according tothe invention, it is usually desirable, and often necessary to employ abinder therewith, such as a binder which is a poly(ethylene oxide)having an average molecular weight of about 100,000 to about 5,000,000.The presence of the binder can aid in prevention of transfer ofundesired residue to the material from which liquid is removed, such astransfer of undesired concentrations of poly(ethylene oxide) to a layerof a photographic element from which water is removed. It can also aidin the removal of liquid.

The binder can be employed in any suitable concentration depending onthe components of the drying element, the support, if one is employed,the material from which liquid is to be removed, the conditions underwhich liquid is to be removed, and the like. Usually about 10% by weightto about 95% by weight binder in a coating according to the invention issufiicient. In the case of a coating containing about 10% by weight of apoly(ethylene oxide) having an average molecular weight of about 6000 toabout 7500 about by weight of a poly(ethylene oxide) having an averagemolecular weight of about 100,000 to about 5,000,000 is especiallysuitable as a binder where moisture is to he removed from a moist layerof a photographic element.

Typical binders include polymeric binders, for example, natural andsynthetic polymers. Polymers as employed herein include homopolymers,copolymers, terpolymers, and other polymeric materials as well asmixtures thereof. It includes polymeric materials which are cross-linkedwith monomeric and/ or polymeric materials. Mixtures of two or morebinders can be employed in a wide range of ratios. The polymeric bindermust be sufficiently solid and must have sufiicient film formingproperties to form coatings with an organic desiccant according to theinvention.

Examples of typical binders include natural and syn thetic resins, suchas poly(ethylene oxide) having an average molecular weight of about100,000 to about 5,000,000; polyvinyl alcohol; poly(acrylic acidesters), e.g., poly(methylmethacrylate); carboxyl derivatives ofcellulose; vegetable gums; cellulose esters; polyvinyl ethers; andsilicones.

Examples of suitable materials which can be employed in the practice ofthe invention as binders and/or as organic desiccants are disclosed, forexample, in French Pat. 1,482,699, issued Apr. 17, 1967. Specificexamples of materials which can be employed in the practice of theinvention as binders and/or as organic desiccants, depending on theproperties described, are as follows:

(1) Poly(ethylene oxide), usually available as mixtures having anaverage molecular Weight of about 900 to about 20,000. Compounds of thistype are available under the trade name, Carbowax, from Union CarbideCorporation, New York, NY.

(2) Poly(ethylene oxide, having a molecular weight of at least about100,000 and having a narrow melting point range, e.g. about 65 C.Compounds of this type. are commercially available under the trade name,Polyox, from Union Carbide Corporation, New York, NY.

(3) Poly(acrylamide) and related polyamides, such as those having anaverage molecular weight of at least about 900, e.g. 900 to 5000.

(4) Polyvinylpyrrolidones, such as those having an average molecularweight of at least about 900, e.g. about 900 to about 40,000 or more.

Alkylene oxide-silicone copolymers. Compounds of this type are availablefrom the Union Carbide Corporation, New York, N.Y. under the trade name,Silicone Polymers L-ZSO, L-S 3 0, and the like.

(6) Ethylene oxide-propylene oxide copolymers in which the ethyleneoxide comprises at least 40% by weight of the copolymer, such as thosehaving an average molecular weight of at least about 900, eg about 900to about 20,000. Compounds of this type are available under the tradename Pluronic from Wyandotte Chemical Company, Wyandotte, Mich.

(7) Polyvinyl glycols, such as those having an average molecular weightof at least about 900, e.g. about 900 to 9,000.

(8) Urethane resins, such as those having an average molecular weight ofat least about 900. Compounds of this type are available, for instance,from the Dow Chemical Company, Midland, Mich. under the trade name,Voranol.

(9) 'Polyacryloxy sulfonic acids, such as those having an averagemolecular Weight of at least about 900. Corn pounds of this type canremove water from layers of a photographic element, i.e. they can be anorganic desiccant and/or a binder according to the invention.

(10) Vinyl ether-maleic anhydride copolymers, such as those having anaverage molecular weight of at least about 900. Compounds of this typeare. available from General Aniline and Film Corporation, New York,N.Y., under the trade name, Gantrez Resin AN-119.

(11) Copolymers of acrylamide with Z-acetoacetoxyethyl methacrylate,e.g. those containing 90% by weight acrylamide.

While various polymeric coatings can be used for removing difiusibleliquid according to the invention, especially poly(ethylene oxide),having an average molecular weight of about 190 to about 5,000,000 areespecially suitable, for instance, (a) alone, (b) as a binder, (c) partof a mixture of binders or (d) part of a mixture of drying agents andbinders.

High molecular weight poly(alkylene oxide) as employed herein means suchcompounds having an average molecular weight Well above 20,000, e.g.above the highest average molecular weight of poly(ethylene oxide) soldunder the trade name, Carbowax, by the Union Carbide Corporation, NewYork, N.Y., and typically at least about 100,000, e.g. about 100,000 toabout 500,000 or more.

Highly crystalline, as employed herein, means that the polymer in thesolid state has a sharp melting point, e.g. about 65 C. for highmolecular weight poly(ethylene oxides). The degree of crystallinity cantypically be measured using nuclear magnetic resonance techniques.

A coating of the invention can contain an inorganic desiccant. Anysuitable inorganic desiccant can be employed which does not adverselyaffect the material dried, does not leave an undesirable residue anddoes not adversely affect the removal of liquid by the coating of theinvention. For example, the inorganic desiccant set out in British Pat.1,012,391 or inorganic drying agents known in the art as molecular sievematerials can be employed in combination with an organic desiccant ofthe invention. Suitable molecular sieve materials are described, forexample, in an article by Rene Petit (University of Paris), in Chim.Anal. (Paris), vol. 47, No. 12, pp. 643 to 656 (1965).

The addition of molecular sieve materials according to the invention canproduce an advantageous reduction in possible undesirable adhesion of acoating of the invention to the materials from which ditfusible liquidis to be removed. For example, the addition of a crystalline aluminosilicate molecular sieve material to a coating of the invention canproduce a pronounced decrease in adhesion of a coating of the inventionto a photographic element. The concentration of inorganic desiccantand/or method of preparation of a coating according to the inventioncontaining an inorganic desiccant can vary depending upon components inthe coating, the material to be dried, the type of support, if one isemployed, and the like. In general, less than about by weight, e.g.about 0.01% to about 50% by weight of the total coating is inorganicdrying agent. The inorganic drying agent can be admixed in a coatingcomposition before coating on a suitable support, if one is employed,can be applied to or prepared in the support before application of othercomponents of the coating can be applied in a separate layer or can beapplied in any suitable manner.

The invention is useful for drying and/or removing diffusible liquidfrom a wide range of permeable solid materials containing such liquid.For instance, the elements, compositions and processes of the inventioncan be used for drying or removing liquid from:

(a) textile fibers and/or fabrics, such as removing moisture from moistnatural or synthetic fibers;

(b) coatings of various types, such as removing moisture from a moistgelatino coating; or

(c) inked or printed surfaces, such as surfaces where ordinary inkblotters are useful.

In removing dilfusible liquids from such materials, it is important thatthe material to be dried be intimately contacted with the materialsaccording to the invention which effect removal of the liquid.

A semi-permeable membrane material, such as a thin sheet of cellophane,can be used between the permeable material from which diftusible liquidis to be removed and a coating according to the invention, if desired.The semipermeable membrane material can be applied to the permeablematerial to be dried and/ or to the coating according to the invention.The semipermeable membrane can also prevent undesired transfer ofmaterials to a coating of the invention or to the support containing thecoating.

A coating according to the invention can be employed more than once. Forinstance, a single solid coating comprising a mixture of a poly(ethyleneoxide) having a molecular weight of about to about 20,000 with poly-(ethylene oxide) having an average molecular weight of 100,000 to5,000,000, about 1.0 to about 4.0 mils thick on a paper support can beemployed for removing more than 90% by weight of the water from at leastsix pieces of moist photographic film using a contact time of less thantwo minutes for each piece of film.

In general, any diffusible liquid can be removed from a permeable solidaccording to the invention which is more strongly attracted to a dryingelement of the invention than said permeable solid when the dryingelement and permeable solid are intimately contacted. Suitablediffusible liquids include, for example, water, methanol, liquid loweralkyl amines, such as ethyl amine, and lower alkanol amines, such asethanol amine and propanol amine.

The theory by which diffusible liquids are removed according to theinvention is not understood. However, it is believed that in the case ofa poly(ethylene oxide), the diffusible liquid forms hydrogen bonds withthe poly- (ethylene oxide). Hydrogen bonding between materials isdescribed, for example, in The Hydrogen Bond by Pimental and McClellan,W. H. Freeman and Company, San Francisco, 1960.

Various addenda can be present in and/ or on the coating and/or asupport, if one is employed, according to the invention, especiallythose known to be beneficial in photographic elements, compositions andprocesses. The materials from which the ditiusible liquid is removed canalso contain such addenda. The types of addenda and suitableconcentrations can be determined by those skilled in the art. Suitableaddenda include, for example, hardeners, such as those set out inBritish Pat. 974,317; buffers, such as various sulfonamides and boraxes;coating aids; plasticizers; speed-increasing addenda; stabilizing agentsand the like.

It has also been found that various sugars, e.g. sucrose and dextrose,can be included in a coating of the invention. The amount which issuitable can vary depending on the coating components, the solidmaterial from which liquid is to be removed, and the like. For example,a composition which can be employed for preparing a coating for drying amoist photographic element comprises about 1 to about 1000 grams ofsucrose and/or dextrose per liter of coating composition.

In contacting material from which liquid is to be removed and a solidcoating containing an organic desiccant according to the invention awide range of pressure can be employed. It is not necessary, and oftenundesirable, to employ high pressure in contacting the materialsaccording to the invention, e.g. pressures of more than about 50kilograms per square centimeter can be undesired. Any suitable means canbe employed for contacting the materials, e.g. in the case of aphotographic element it is suitable to pass the photographic element andthe drying element of the invention between rollers, or to place thephotographic element on a stationary solid surface and press the dryingelement onto the element.

The time required for removal of diffusible liquid from a peremablesolid can vary depending on many factors, such as the material to bedried, the amount and type of liquid to be removed, the components ofthe coating em ployed for removing the liquid, and the like. In general,coatings according to the invention can remove a diffusible liquid froma permeable solid, such as a layer of a photographic element, containingthe liquid in less than about 120 seconds, e.g. about 1 to about 60seconds. For instance, a typical coating according to the inventioncomprising a mixture of a poly(ethylene oxide) having a molecular weightof about 6000 to 7500 with a high molecular weight, highly crystallinepoly (ethylene oxide) can remove more than 90% of the water in a moistphotographic element under ambient conditions, e.g. a temperature ofabout C. to about C., in less than 60 seconds, and usually in a fractionof a second up to 15 seconds. If necessary, however, longer time ofcontact between the drying element of the invention and the materialfrom which liquid is to be removed can be employed.

The temperatures, pressures, and humidities which are suitable for useaccording to the invention can vary over wide ranges. Usually ambienttemperature, pressure and humidity are suitable; however, in some casesit can be desirable to use and/ or store the coatings of the inventionunder controlled conditions, for example, to avoid unnecessary prematuretake-up of moisture from the air when the coating is to be employed toremove water from a moist photographic element under conditions of highhumidity and/or temperature, e.g. under tropical conditions.

A drying element of the invention can be stored and/ or packaged in anysuitable container, e.g. in foil and/or plastic Wrappers, which are airand/ or moisture tight, before use.

Any support, if one is employed, can be used for a coating of theinvention and such a support can be in any suitable shape or form. Theseinclude those commonly employed in the photographic art, such as films,including cellulose acetate films, polyester films, such as polyethyleneterephthalate films, polyvinyl acetal films, polystryrene films,polycarbonate films, and related materials, papers, e.g. paper supportscoated with resinous materials e.g., coated with polyethylene,polypropylene, and/ or ethylene-butene copolymers, glass, fabrics, metaland the like. Supports in the form of webs or tapes can be used, forexample. Supports which act as a reservoir for diffusible liquid removedare especially suitable. For this reason, absorbent fibrous materialsformed from, for example, textile or glass fibers, paper and/ or similarwater absorb ent supports can be especially useful.

A drying element and/or process of the invention is useful for rapidlyremoving diffusible liquid from a wide variety of photographic elementscontaining such liquid. For example, it can be used for removing waterfrom any suitable photographic element in a moist condition.

Photographic elements employed in the practice of the invention containa layer comprising any of the known Water permeable binding materialssuitable for photo graphic purposes. These include, for example,gelatin, cellulose derivatives, polymerized vinyl compounds, as well asmixtures of such binding agents. These binding agents can contain waterinsoluble polymers, such as polymerized ethylentically unsaturatedcompounds, e.g. polymers of acrylates and methacrylates.

The photographic elements which can be dried according to the inventioninclude, among others, those which contain a photographic silver saltemulsion, e.g. a silver halide gelatino emulsion layer, or a non-silverhalide emulsion. These can be non-spectrally sensitized emulsions, suchas X-ray type emulsions, or they can be orthochromatic, panchromatic,infrared sensitive, and the like emulsions containing spectralsensitizing dyes, such as described in U.S. Pats. 2,526,632 and2,503,776. Spectral sensitizers which can be used include cyanines,merocyanines, styryls and hemicyanines.

For example, the invention can be employed for removing diffusibleliquid, such as water, from layers of photographic elements used forcolor photography, e.g. it can be used for drying films and/or printsused in color photography, such as emulsions containing color-formingcouplers or emulsions developed by solutions containing couplers orother color generating materials; emulsions of the mixed-packet type,such as described in U.S. Pat. 2,698,794 of Godowsky, issued Jan. 9,1955; or emulsions of the mixed grain type, such as described in U.S.Pat. 2,592,243 of Carroll and Hanson.

The drying element and/or processes of the invention can be used inprocessing emulsions intended for use in diffusion transfer processeswhich utilize undeveloped silver salts in the non-image areas of thenegative to form a positive by dissolving the undeveloped silver saltsand precipitating them on a receiving layer in close proximity to theoriginal silver salt emulsion layer. Such processes are described, forexample, in U.S. Pat. 3,020,155 of Yackel et al., issued Feb. 6, 1962;U.S. Pats. 2,584,029, issued Jan. 29, 1952; 2,698,236, issued Dec. 28,1954'; and 2,543,181, issued Feb. 27, 1951, of E. H. Land and U.S. Pat.2,352,014 of Rott, issued June 20, 1944. The invenvention can also beused in color transfer processes which utilize the difiusion transfer ofdeveloper, coupler or dye, from a light sensitive layer to a secondlayer, such as described in U.S. Pat. 2,559,643 of Land, issued July 10,1951; U.S. Pat. 2,698,798, issued Jan. 4, 1955; U.S. Pat. 2,756,142 ofYutzy, issued July 24, 1956; U.S. Pat. 3,252; 915 of Weyerts et al.,issued May 31, 1966; and U.S. Pat. 3,227,550 of Whitman et al., issuedJan. 4, 1966.

The invention can be used in processing emulsions used in lithography,preparation of direct prints, or in colloid transfer processes as wellas in processing of elements using monobath processes, such as describedin U.S. Pat. 2,875,048 of Haist et al., issued Feb. 24, 1959, andwebtype processing such as described in U.S. Pat. 3,179,517 of Tregilluset al. It can also be used in so-called stabilization processing, suchas processing an element containing an incorporated developer through anactivator bath containing a thiocyanate stabilizer, as described, forexample, in British Pat. 1,061,892, issued Mar. 15, 1967, or in anarticle titled Stabilization Processing of Films and Papers by H. D.Russel, E. C. Yackel and J. S. Bruce, P.S.A. Journal, August 1950, pages59-62.

The drying elements and/or processes of the invention can be employed inthe production of layers of liquid permeable solid materials. Forinstance, the flexible, liquid permeable, drying elements and processesof the invention can be employed in the production of layers ofunexposed photographic elements which require removal of water and/orother suitable liquid at some stage. A typical process according to theinvention for the production of a layer of a photographic elementaccordingly comprises applying a hydrophilic colloid coating to asubstrate, the resulting coating containing water and/ or other suitableliquid, and subsequently contacting the hydrophilic colloid coating witha flexible, liquid permeable, drying element comprising an organicdesiccant, to remove a substantial portion of the water and/or othersuitable liquid from the hydrophilic colloid coating.

A wide range of coating methods and conditions can be employed forpreparing the coatings from which liquids, e.g. water, can be removedaccording to the inventlon. In general, coating methods, compositions,and conditions commonly employed in the photographic art can beemployed.

A typical method for production of a raw photographic emulsion layercomprises applying a coating of a photographic emulsion to a substrate,setting the resulting coating, such as by chilling or fuming withammonia 1n the case of gelatino emulsion coatings, and contacting theresulting coating with a flexible, liquid permeable, drying elementcomprising an organic desiccant. For instance, a raw, wet, photographicemulsion coating can be contacted with a solid, flexible, coatingcomprising an organic desiccant, such as contacted with a supported orunsupported coating containing a poly(ethylene oxide) and/or one of theorganic desiccants described, to remove a substantial portion of theWater from the raw photographic emulsion coating.

The raw photographic emulsion coating can be contacted using essentiallythe same conditions and time of contact as employed for contactingexposed and processed, wet photographic elements to efiect removal ofWater.

One of the useful characteristics of a coating of the invention is thatin removing ditfusible liquid from a permeable solid, certain solidmaterials dissolved in the diffusible liquid are also substantiallyremoved from the permeable solid. For example, certain compounds in aphotographic element containing a diffusible liquid can be removed fromthe element with the difiusible liquid according to the invention. Thesecompounds in the case of a photographic element processed with one ormore aqueous processing solutions, e.g. a monobath, a stabilizer bath ora bath causing some of the compounds in the elernerg to become watersoluble, such as silver halide solvents, are usually water soluble. Whenthe moist element containing such compounds is contacted with a dryingelement according to the invention these compounds are removed from theelement with the water removed. For instance, in processing aphotographic element using Web processing techniques as set out, forexample, in U.S. Pat. 3,179,517 of Tregillus et al., certain processingagents are present in the moist processed element. A significant amountof these processing agents and other water soluble compounds formed inprocessing, such as a water soluble complex formed between unexposedsilver halide and a silver halide solvent, are removed from the elementwhen a coating according to the invention is contacted with the moistprocessed element. The concentrations and types of compounds removedfrom the moist photographic element can vary over a Wide range and willdepend on many factors such as the type of element, the type ofprocessing carried out, the coating according to the invention employed,and the like.

A Wide variety of coating compositions and means for applying them canbe employed for preparing the coatings of the invention. In general, anycomposition, coating means or coating process which provides an adherentcoating, having the desired thickness, the desired amounts ofcomponents, and the desired liquid removal properties can be employed.It is often advantageous to employ an organic solvent in the coatingcomposition. Any organic solvent is suitable which provides the desiredcoating and can be selected by those skilled in the coating art. Aqueoussolvents have been found especially useful, such as mixtures of waterand a water miscible alcohol, e.g. methanol or acetonitrile.

An especially suitable coating composition comprises a mixture of:

(a) About to about by weight of the total composition solvent,comprising about 10% to about 20% by volume Water and about 80% to about90% by volume water miscible organic solvent, e.g. water misciblealcohol such as methanol, and

(b) About 10% to about20% by weight of the total composition solidssoluble in the said solvent comprising about 50% to by weight watersoluble, high molec ular weight, highly crystalline poly(alkyleneoxide), e.g. poly(ethylene oxide), and 0% to 50% by weight poly(alkyleneoxide) having a molecular weight of about to about 20,000, e.g.poly(ethylene oxide). For example, a coating composition within thescope of this embodiment comprises a mixture of:

(l) About 85% by Weight solvent comprising about 15 by volume Water andabout 85% by volume methanol, and

(2) About 15% by weight solids, comprising about 10% by weightpoly(ethylene oxide) having an average molecular Weight of about 6000 to7500 and a high molecular weight, highly crystalline poly(ethyleneoxide). Such compositions are typically viscous mixtures.

Another embodiment of the invention is in a process for removing adiifusible liquid from a permeable solid containing said liquid bycontacting said permeable solid with a solid material which removes saidliquid from said permeable solid, the improvement comprising contactingsaid permeable solid with a flexible, liquid permeable, drying elementcomprising a solid coating containing an organic desiccant.

According to the invention, any method of and/or means for contactingthe permeable solid containing the difiusible liquid and the solidcoating of the invention can be used which provides the desired removalof liquid from the permeable solid. A coating of the invention can, forexample, be on a fiat, vertical, horizontal, or angular surface, on acontinuous web, or it can be on a drum or cylinder, such as one whichrotates, which contacts the permeable solid, e.g. a moist photographicelement. It is important, however, that the method and means employedprovide intimate contact. One method which is suitable compriseswrapping a flexible support, e.g. a paper Web, coated on one or bothsides with a coating according to the invention, on a common core with amoist photographic element, e.g. a roll of moist photographic film.

The amount of solid coating per square foot suitable according to theinvention can vary over wide ranges depending on the components of thecoating, the material to be dried and the like. A coating consisting of,for example, about 3 grams to about 30 grams, typically about 4 to about10 grams per square foot, in and/or on a support, if one is used, can besuitable for removing moisture from a moist photographic element.

A typical process within this embodiment comprises removing moisturefrom a moist photographic element by contacting said element with asolid coating comprising a mixture of a poly(ethylene oxide) having anaverage molecular weight of about 190 to about 20,000 and a highmolecular weight poly(ethylene oxide), e.g. a poly- (ethylene oxide)having an average molecular weight of about 100,000 to about 5,000,000.In such a process at least about 60% by weight, and typically at leastabout 85% by weight, of water is removed from said element in about 1 toabout 60 seconds at about 20 C.

For example, moisture can be removed from a moist photographic elementby contacting said element for up to about 60 seconds under ambientconditions of temperature, pressure and humidity with a drying elementWhlCh lS a paper or film support having a solid coating comprising amixture of poly(alk ylene oxide) having an average molecular weight ofabout 190 to about 20,000 with a high molecular weight poly(alkyleneoxide) about 0.01 millimeter to about 1.0 millimeter thick to remove atleast about 90% by weight of said moisture from said element.

The drying element and processes of the invention are especially usefulin a method of processing an exposed photographic element comprisingcontacting said element with a matrix such as a liquid permeable film orsheet of paper, containing a monobath, such as described in The MonobathManual by Grant M. Haist, 1966, to produce the desired image and dryingthe resulting moist element by contacting said element with a solidcoating comprising about by weight poly(ethylene oxide) and about 90% byweight polymeric binder, for instance, by contacting said element with asolid coating comprising about 10% by weight poly(ethylene oxide) havingan average molecular weight of about 6000 to about 7500 with about 90%by weight of high molecular weight poly(ethylene oxide).

The invention is further illustrated in the following examples. Unlessotherwise indicated, percentages employed herein are by weight.

EXAMPLE 1 This example illustrates removing moisture from a processed,moist photographic film according to the invention.

A piece of photographic film containing a medium grain silverbromoiodide gelatino emulsion layer on a polyethylene terephthalatesupport is exposed imagewise to light. The film is 35 mm. Wide and 25.4centimeters long. The exposed film is processed using conventionalsilver halide developer and stabilizer baths, i.e. Kodak D-85 developerand Kodak F-5 Fixer. It is then washed for several minutes in waterafter which water on the surface of the film is removed by wiping.

A so-called drying tape, i.e. a paper support containing a coatingaccording to the invention, is placed in intimate contact with the moistfilm under room conditions, i.e. about 21 C. and about 50% relativehumidity, for seconds by pressing the drying tape on the emulsion sideof the film.

The drying tape in this example is a paper support about 0.1 millimeterthick having a 0.114 millimeter solid coating of a mixture of 10% byweight poly(ethylene oxide) having an average molecular weight of about6000 to 7500 (Carbowax 6000, produced by Union Carbide Corporation, NewYork, N.Y.) with 90% by weight poly- (ethylene oxide) having an averagemolecular weight of about 600,000 (Polyox WSR 3000, produced by UnionCarbide Corporation, New York, N.Y.). The coating is prepared by coatinga composition consisting of a viscous aqueous methanol solution of thepoly(ethylene oxide) compounds on the paper support with a doctor blade.

At least 90% of the moisture is removed from the moist film and nopoly(ethylene oxide) residue is observable on the film employing thisprocedure and coating according to the invention.

EXAMPLE 2 This example illustrates removing moisture from a photographicfilm according to the invention which is processed using web processingaccording to U.S. Pat. 3,179,517 of Tregillus et al., issued Ap. 20,1965.

A processing web is prepared by soaking a hydrolyzed cellulose acetatefilm support in a 0.1% gold chloride solution for 3 minutes and then ina 0.2% solution of N- methyl-p-aminophenol sulfate. It is washed 5minutes in Water and then soaked for 5 minutes in a solution comprising:

Grams 1-phenyl-3-pyrazolidone 1.0

Hydroquinone 10.0 Z-dimethylaminoethanol-SO addition product mol percentS0 174.0

Sodium thiosulfate peutahydrate 2.0

Water to make 1 liter.

The excess liquid on the surface of the resulting processing web isremoved with a squeegee.

A so-called drying tape is prepared as set out in Example 1.

A piece of photographic film having a medium grain silver bromoiodidegelatino emulsion having a total thickness in dry condition of 108microns is exposed imagewise to light. It is then rolled in contact withthe described processing web for a few minutes until full development ofthe exposed film occurs. The film and processing web are then peeledapart.

The resulting moist film having a total thickness of 130 microns is thencontacted with the described drying tape for 15 seconds. This produces afilm which is substantially dry and has no poly(ethylene oxide) residueobservable on the film.

EXAMPLE 3 This example illustrates drying of a photographic film using acoating and process of the invention.

A photographic film containing a medium grain silver bromoiodidegelatino emulsion layer, prehardened during manufacture, is exposedimagewise to light. It is then processed in processing solutions andapparatus as described in U.S. Pat. 3,179,517-Tregillus et al., issuedApr. 20, 1965. The film is washed in water at about 20 C. for a periodof two minutes. It is removed from the Water, each surface wiped toremove surface moisture, and placed on a clean, dry, smooth, polishedmetal surface.

A drying tape is prepared as described in Example 1, containing acoating 0.114 millimeter thick consisting of 50% by weight poly(ethyleneoxide) having an average molecular weight of about 1300 to about 1600(Carbowax 1540, produced by Union Carbide Corporation. New York, NY.)and 50% by weight highly crystalline poly- (ethylene oxide) having anaverage molecular weight of about 600,000 (Polyox WSR-N3000) is pressedonto the moist film.

Within 15 seconds at least of the moisture in the film is removed. Noobservable poly(ethylene oxide) residue is left on the film after thedrying tape is removed from the film.

EXAMPLE 4 The procedure set out in Example 3 is repeated with theexception of using a coating 0.127 millimeter thick consisting of highmolecular weight poly(ethylene oxide) (Polyox WSRN4000, produced byUnion Carbide Corporation, New York, NY.) having a melting point ofabout 65 C. on the paper support.

Substantially the same results are obtained as in Example 3.

EXAMPLE 5 The procedure set out in Example 3 is repeated with theexception of using a coating 0.152 millimeter thick consisting of 50% byweight poly(ethylene oxide) having an average molecular weight of 6000to 7500 (Carbowax 6000) and 50% by weight poly(ethylene oxide) having anaverage molecular weight of about 600,000 (Polyox WSRN3 000) on thepaper support.

Substantially the same results are obtained as in Example 3.

EXAMPLE 6 The procedure set out in Example 3 is repeated with theexception of using a coating 0.152 millimeter thick consisting of 50% byweight poly(ethylene oxide) having an average molecular weight of 380 to420 (Carbowax 400, produced by Union Carbide Corporation, New York, NY.)and 50% by weight poly(ethylene oxide) having an average molecularweight of about 600,000 (Polyox WSRN3000) on the paper support.

Substantially the same results are obtained as in Example 3.

EXAMPLE 7 The procedure set out in Example 3 is repeated with theexception of using a coating 0.152 millimeter thick con- 13 sisting of50% by weight poly(ethylene oxide) having an average molecular weight of570 to 630 (Carbowax 600, produced by Union Carbide Corporation, NewYork, N.Y.) and 50% by Weight poly(ethylene oxide) having an averagemolecular weight of about 600,000 (Polyox WSR-N-3000) on the papersupport.

Substantially the same results are obtained as in 'Example 3.

EXAMPLE 8 The procedure set out in Example 3 is repeated with theexception of using a coating 0.114 millimeter thick consisting of 100%by Weight highly crystalline poly (ethylene oxide) having an averagemolecular weight of about 600,000 (Polyox WSR-N3000) on the papersupport.

Substantially the same results are obtained as in Example 3.

EXAMPLE 9 The procedure set out in Example 3 is repeated with theexception of using a coating 0.140 millimeter thick consisting of 25% byweight poly(ethylene oxide) having an average molecular weight of 570 to630 (Carbowax 600) and 75% by Weight high molecular weight, highlycrystalline poly(ethylene oxide) (Polyox WSRN3000) on the paper support.

Within seconds at least 90% of the moisture in the film is removed. Noobservable residue is left on the film.

EXAMPLE 10 This example illustrates the use of sugars, such as sucrose,in the practice of the invention.

The procedure set out in Example 3 is repeated with the exception ofusing a coating 0.203 millimeter thick consisting of 50% by weightordinary table sugar, i.e. sucrose, and 50% by weight high molecularweight, highly crystalline poly(ethylene oxide) (Polyox WSR-N-3000) onthe paper support.

Within 5 seconds at least 90% of the moisture in the film is removed.

EXAMPLE 11 This example illustrates the use of sugars in the practice ofthe invention.

The procedure set out in Example 3 is repeated using a coating 0.229millimeter thick consisting of 10% by Weight poly(ethylene oxide) havingan average molecular weight of about 6000 to 7500 (Carbowax 6000), 45%by weight high molecular weight highly crystalline poly (ethylene oxide)(Polyox WSR-750, produced by Union Carbide Corporation, New York, N.Y.)and 45% by weight ordinary table sugar, i.e. sucrose, on the papersupport.

About 90% of the moisture in the film is removed within about 5 seconds.

EXAMPLE 12 The procedure set out in Example 3 is repeated using acoating 0.127 millimeter thick consisting of 6% by weight poly(ethyleneoxide) having an average molecular weight of 6000 to 7500 with 94% byweight poly(ethylene oxide) having an average molecular Weight of about300,000 (Polyox 'WSR-N-750) on the paper support.

Substantially the same results are obtained as in Example 3.

EXAMPLE 13 The procedure set out in Example 3 is repeated using acoating 0.107 millimeter thick consisting of 100% by weightpoly(ethylene oxide) having an average molecular weight of about4,000,000 (Polyox WSR-301, produced by Union Carbide Corporation, NewYork, N.Y.) on the paper support.

At least 90% of the moisture in the film is removed within 30 seconds.

14 EXAMPLE 14 The procedure set out in Example 3 is repeated using acoating 0.127 millimeter thick consisting of 10% by weight poly(ethyleneoxide) having an average molecular weight of about 6000 to 7500(Carbowax 6000) and 90% by weight poly(ethylene oxide) having an averagemolecular weight of about 200,000 (Polyvox WS R35, produced by UnionCarbide Corporation, New York, N.Y.) on the paper support.

At least 90% of the moisture in the film is removed within 5 seconds.

EXAMPLE 15 The procedure set out in Example 3 is repeated using acoating 0.178 millimeter thick consisting of 100% poly (ethylene oxide)having an average molecular weight of about 200,000 (Polyox WSR35) onthe paper support.

At least 90% of the moisture in the film is removed within 5 seconds.

EXAMPLE .16

This example illustrates the use of an inorganic desiccant in a coatingaccording to the invention.

The procedure set out in Example 3 is repeated with the exception ofusing a coating consisting of 10% by weight poly(ethylene oxide) havingan average molecular weight of about 6000 to 7500 (Carbowax 6000), byweight poly(ethylene oxide) having a molecular Weight of about 600,000(Polyox WSRN3000) and 5% by weight crystalline alumino silicatemolecular sieve material on the paper support.

At least of the moisture in the film is removed within 5 seconds. Also,increased moisture capacity as well as decreased adhesion between thefilm and drying tape are observed in comparison to coatings notcontaining the molecular sieve material.

EXAMPLE 17 This example illustrates the use of a semi-permeable membranebetween a material from which diffusible liquid is to be removed and apolymeric coating in the practice of the invention.

The procedure set out in Example 3 is repeated with the exception that astrip of moisture permeable cellophane about 30 centimeters long, about8.25 centimeters wide and about 0.1 mm. thick is soaked in water and,after removing surface moisture, applied between the moist film anddrying tape before the drying tape and moist film are pressed together.Also, a coating consisting of 56% by weight poly(ethylene oxide) havinga molecular weight of about 1300 to about 1600 (Carbowax 1540) and 18%by Weight poly(ethylene oxide) having a molecular Weight of 600,000(Polyox WSlRN3000) is used on the paper support. Some of this mixture isabsorbed into the paper support. The polymer content in and on the papersupport is 4.9 grams per square foot.

About 84% of the moisture is removed from the film within 60 seconds.

EXAMPLE 18 This example illustrates the use of a semi-permeable membranein the practice of the invention.

A drying tape is impregnated with a highly crystalline poly(ethyleneoxide) having a molecular weight of about 600,000 (Polyox WSR-N-3000) bysoaking a paper support in an aqueous solution consisting of 2 grams ofthe poly(ethylene oxide) per liter of Water. The resulting support isallowed to dry under room conditions. producing a paper supportcontaining 18.7 grams of the poly (ethylene oxide) per square foot. Useof this drying tape as set out in Example 3 with a semi-permeable layerof cellophane between the moist film and drying tape as set out inExample 17 removes at least 90% of the moisture from the film within 60seconds.

15 EXAMPLE 19 The procedure set out in Example 1 8 is repeated with theexception that an overcoat consisting of a mixture of 70% by weightpoly(ethylene oxide) having a molecular weight of 570 to 630 (Carbowax600, produced by Union Carbide Corporation, New York, N.Y.) is appliedto the drying tape to produce a total poly(ethylene oxide) content inand on the drying tape of 27.0 grams per square foot.

Substantially the same results are obtained as in Example 18. In thisexample, without the cellophane between the drying tape and the moistfilm, a noticeable residue remains on the film after removal ofmoisture.

EXAMPLE 20 This is a comparative example comprising use of a polymericcoating of the invention for drying a gelatino emulsion in production ofa photographic film to air drying an identical emulsion.

A high contrast photographic silver chlorobromide gelatino emulsion iscoated on a polyethylene terephthalate support at the rate of 351miligrams of silver per square foot and 347 milligrams of gelatin persquare foot. The emulsion is chill set and divided into two equal parts,(A) and (B).

Part (A) is contacted with a drying tape consisting of a paper supportcontaining about 7.5 grams per square foot of a mixture of 10% by weightpoly(ethylene oxide) having a molecular weight of about 6000 to 75(Carbowax 6000) and 90% by Weight poly(ethylene oxide) having amloecular weight of about 600,000 (Polyox WSR-N-3000) in and/ or on thesupport. The coating on the support is about 0.064 millimeter thick.After 15 seconds, the drying tape is removed. The gelatino emulsion isdry to the touch.

Part (B) is air dried using forced air drying at about room temperature.The time required to dry the film is about minutes.

After drying, both (A) and (B) are exposed 5 seconds to a standard stepwedge, developed in Kodak D85 Developer, fixed in Kodak F-5 Fixer,washed in water, and air dried. Part (A) has a 0.52 log E speed losscompared to Part (B) and the surface appears slightly reticulated.

EXAMPLE 21 A solution of by weight highly crystalline poly- (ethyleneoxide) having a molecular weight of about 600,000 (Polyox WSR-N-3000) inacetontitrile is coated on a paper support at the rate of 6.0 grams persquare foot and allowed to dry at room temperature. Some of thepoly(ethylene oxide) is absorbed into the paper. An aqueous 6% by weightgelatin solution is coated on a polyethylene terephthalate support atthe rate of 498 milligrams of gelatin per square foot. The resultingcoating is contacted for seconds with a drying tape as described inExample 20. After removing the drying tape, the gelatin coating is dry.

EXAMPLE 22 A multilayer photographic film containing gelatino silverhalide emulsion, red, green and blue sensitive layers (KodakEktachrome-X film) is soaked in water for several minutes until theemulsion layers are swollen, i.e. from a total support and emulsionthickness in a dry condition of 152 microns to a total thicknes of 242microns. The surface moisture is removed by wiping. The resulting moistfilm i contacted with a drying tape consisting of a paper support havinga coating 0.064 millimeter thick consisting of 7.5 grams per square footof a mixture of 10% by Weight poly(ethylene oxide) having a molecularweight of about 6000 to 7500 (Carbowax 6000) and 90% by weight poly(ethylene oxide) having a molecular weight of about 600,000 (PolyoxWS-R-N-3000). Within 60 seconds, at least 90% of the moisture is removedfrom 16 the moist film, i.e. the total thickness of the support andemulsion layers is 157 microns. No noticeable residue remains on thefilm.

EXAMPLE 23 The procedure set out in Example 22 is repeated with theexception that a coating 0.051 millimeter thick consisting of 10% byweight poly(ethylene oxide) having an average molecular Weight of 6000to 7500 (Carbowax 6000) and by weight of a copolymer of acrylamide with2-acetoacetoxyethyl methacrylate containing 90 by weight acrylamide ison the paper support. Substantially the same results are obtained as inExample 22.

EXAMPLE 24 Several lines of blue ink are placed with a conventional inkpen on a piece of conventional writing paper. A drying tape as describedin Example 22 is contacted with the paper by pressing the drying tapeover the portion of the paper containing the ink lines while the ink isstill moist. The drying tape effects drying of the ink within less than5 seconds without leaving noticeable residue on the writing paper ordistorting the lines.

EXAMPLE 25 This example illustrates use of a multilayer polymericcoating in the practice in the practice of the invention.

The procedure set out in Example 3 is repeated with the exception thatan initial coating consisting of 10% by weight poly(ethylene oxide)having a molecular weight of about 6000 to 7500 (Carbowax 6000), 75% byweight poly (ethylene oxide) having a molecular weight of about 600,000(Polyox WSR-N-3000) and 15% by weight crystalline alumino silicatemolecular sieve material is applied to the paper support and allowed todry followed by application of an overcoat, about the same thickness asthe initial coating, consisting of 10% by weight poly- (ethylene oxide)having a molecular weight of about 6000 to 7500 (Carbowax 6000) and 90%by weight poly( ethylene oxide) having a molecular weight of about600,000 (Polyox WSR-N-3000).

At least 90% of the moisture in the moist film is removed within 15seconds.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

I claim:

1. A flexible, liquid permeable drying element comprising a supporthaving on at least one surface a thin, adherent liquid permeable coatingconsisting essentially of a poly(ethylene oxide) having an averagemolecular weight of at least about 100.000 or said poly(ethylene oxide)having dispersed therein about 10% to 50% by weight of a poly(ethyleneoxide) having an average molecular weight of about to about 20,000.

2. A drying element as in claim 1 wherein said coating has the propertyof removing at least about 60% by weight of water from a wet gelatinlayer coated on a support upon contacting said layer for a period of nomore than 60 seconds with said drying element.

3. A drying element as in claim 1 wherein the high molecular weightpoly(ethylene oxide) has an average molecular weight of about 100,000 toabout 5,000,000.

4. A drying element as in claim 1 wherein said coating is about 0.001millimeter to about 1.0 millimeter thick.

5. A flexible, liquid permeable drying element comprising a papersupport having a coating consisting essentially of a mixture of about10% to 50% by weight poly (ethylene oxide) having an average molecularweight of about 6,000 to 7,500 With about 90% by weight poly (ethyleneoxide) having an average molecular weight of about 100,000 to about5,000,000.

17 18 6. A flexible, liquid permeable drying element compris- 2,388,39011/1945 Cook et .al. 252194 ing a support having coated on at least onesurface at 3,146,272 8/1964 Lloyd 252-194X least one thin, adherent,liquid permeable coating consist- 3,164,560 1/1965 Suter 117 161X ingessentially of a poly(ethylene oxide) having an aver- 3 320,0 5 19 7 ild117 1 1X age molecular Weight of at least about 100,000 or said 5 235742 11 9 Wagner 1 7 1 1X poly(ethylene oxide) having dispersed thereinabout 10% to 50% by weight of a poly(ethylene oxide) having an averagemolecular weight of about 190 to about 20,000 said coating furthercontaining an alumino silicate molec- 3,397,074 8/1968 Alles 117-161XWILLIAM D. MARTIN, Primary Examiner ular Slave material- 10 H. J. G.WINNELL, Assistant Examiner References Cited UNITED STATES PATENTS2,842,223 7/1958 Zall 55524X 34-9; 9648; 117-161 3,384,971 5/1968 Thomaset a1 34-9 15

